1. Field of the Invention
The present invention relates to a solar cell backsheet including a fluorine-based resin layer and a substrate layer, and more particularly, to a solar cell backsheet having improved heat-resistance and durability, a method of manufacturing the solar cell backsheet, and a solar cell including the solar cell backsheet.
2. Discussion of Related Art
Lately, the problem of global warming has attracted the attention of several fields, and there are various ongoing efforts to reduce carbon dioxide emissions. Increase in the consumption of fossil fuels leads to an increase in atmospheric carbon dioxide, which has numerous adverse effects on the global environment, including global temperature rise via the greenhouse effect. To solve these problems, various studies are underway. In particular, expectations for photovoltaic power generation are increasing due in large part to its clean, pollution-free characteristics.
The core of a photovoltaic power generation system that directly converts the energy of solar rays into electricity is a solar cell made of a monocrystalline, polycrystalline, or amorphous silicon-based semiconductor. In the structure of a solar cell, solar cell devices are arranged in series or parallel, and several types of packaging are performed to unitize and protect the cell for a long time (about 20 years). The resulting units are referred to as solar cell modules.
In general, the solar cell has a constitution in which a surface hit by solar rays is covered by glass, a gap is filled with a filler that is a thermoplastic material (particularly, ethylene-vinyl acetate copolymer (EVA)), and the opposite surface is protected with a white sheet made of a heat- and weather-resistant plastic.
Since performance of solar cells needs to be maintained for about 20 years, a fluorine-based resin has been used as a rear surface protection sheet for durability, weather-resistance, etc. However, the fluorine-based resin has low mechanical strength and it is degraded at a temperature of 140 to 150° C. of a heat press performed to manufacture a solar cell module, and also is expensive, hindering the reduction of solar cell module prices.
As the fluorine-based resin, a polyvinylidene fluoride (PVDF) resin mixed with about 30 wt % acrylic resin exhibits optimal properties of adhesion, toughness, optical transparency, etc. However, the PVDF/acrylic resin blend generally has a lower hardness, abrasion, etc. than the PVDF resin.
Consequently, there is a need to develop a backsheet that is low-priced and has improved heat-resistance, weather-resistance, etc.